Channel access procedures for directional systems in unlicensed bands

Abstract

A method to reserve a directional channel, such as in an unlicensed spectrum for instance, is disclosed. In an example embodiment, the method may be performed by a receiving node, such as a user equipment (UE) for instance. In such method, the receiving node may receive an enhanced directional transmit request message from a transmitting node and transmit an enhanced directional transmit confirmation message using one or more first beams, with at least one first beam being directed in a first direction towards the transmitting node. Further, the receiving node may transmit at least one additional enhanced directional transmit confirmation message using one or more second beams, with at least one second beam being directed in a second direction towards a potentially interfering node. In the method, the second direction is a different direction than the first direction.

What is claimed: 
     
       1. A method performed by a first node to reserve a directional channel, the method comprising:
 performing a first listen-before-talk (LBT) in a first beam direction towards a second node to which the first node intends to transmit; 
 detecting a first interfering signal based on the performed first LBT; 
 performing a second LBT in a second beam direction; 
 detecting a second interfering signal based on the performed second LBT; 
 determining a set of transmission parameters based on the determinations of the first and second LBT; 
 transmitting a transmission to the second node using the determined set of transmission parameters; 
 determining a set of LBT parameters of the second LBT based on a beam direction of the first LBT; and 
 performing the second LBT in the second beam direction according to the determined set of LBT parameters. 
 
     
     
       2. The method of  claim 1 , wherein the determined set of transmission parameters comprises any of a beamwidth configuration, a modulation coding scheme (MCS), a transmission backoff time, a number of predefined beams and a transmission power. 
     
     
       3. The method of  claim 1 , wherein the determination of the set of transmission parameters further comprises interfering signal level of the first and of the second interfering signal. 
     
     
       4. The method of  claim 1 , comprising receiving, from the second node, a message comprising configuration information on a directional channel of transmission/reception with the first node;
 determining a set of LBT parameters of the second LBT based on the received message; and 
 performing the second LBT in the second beam direction according to determined set of LBT parameters. 
 
     
     
       5. The method of  claim 4 , wherein the set of LBT parameters of the second LBT comprises any of a number of beams, a beamwidth, a beam direction and an energy detection threshold. 
     
     
       6. The method of  claim 1 , wherein the determined set of LBT parameters of the second LBT comprises any of a number of beams, a beamwidth, a beam direction, and an energy detection threshold. 
     
     
       7. The method of  claim 1 , comprising determining an energy detection threshold as a function of the determined set of LBT parameters of the second LBT, wherein determining if a second interfering signal is detected comprises comparing the second interfering signal with the energy detection threshold. 
     
     
       8. The method of  claim 1 , wherein performing the second LBT in the second beam direction is a function of a set of LBT parameters, and wherein the set of LBT parameters is determined based on hybrid automatic repeat request received from the second node. 
     
     
       9. A wireless transmit/receive unit (WTRU) configured to reserve a directional channel, the WTRU comprising:
 a processor; and 
 a memory storing a plurality of instructions that, when executed by the processor, cause the processor to:
 perform a first listen-before-talk (LBT) in a first beam direction towards a second WTRU to which the WTRU intends to transmit; 
 detect a first interfering signal based on the performed first LBT; 
 perform a second LBT in a second beam direction; 
 detect a second interfering signal based on the performed second LBT; 
 determine a set of transmission parameters based on the determinations of the first and second LBT; 
 transmit a transmission to the second WTRU using the determined set of transmission parameters; 
 determine a set of LBT parameters of the second LBT based on a beam direction of the first LBT; and 
 perform the second LBT in the second beam direction according to the determined set of LBT parameters. 
 
 
     
     
       10. The WTRU of  claim 9 , wherein the determined set of transmission parameters comprises any of a beamwidth configuration, a modulation coding scheme (MCS), a transmission backoff time, a number of predefined beams and a transmission power. 
     
     
       11. The WTRU of  claim 9 , wherein the determination of the set of transmission parameters further comprises interfering signal level of the first and of the second interfering signal. 
     
     
       12. The WTRU of  claim 9 , further configured to:
 receive, from the second WTRU, a message comprising configuration information on a directional channel of transmission/reception with the WTRU; 
 determine a set of LBT parameters of the second LBT based on the received message; and 
 perform the second LBT in the second beam direction according to determined set of LBT parameters. 
 
     
     
       13. The WTRU of  claim 12 , wherein the set of LBT parameters of the second LBT comprises any of a number of beams, a beamwidth, a beam direction and an energy detection threshold. 
     
     
       14. The WTRU of  claim 9 , wherein the determined set of LBT parameters of the second LBT comprises any of a number of beams, a beamwidth, a beam direction, and an energy detection threshold. 
     
     
       15. The WTRU of  claim 9 , further configured to:
 determine an energy detection threshold as a function of the determined set of LBT parameters of the second LBT, 
 wherein determining if a second interfering signal is detected comprises comparing the second interfering signal with the energy detection threshold. 
 
     
     
       16. The WTRU of  claim 9 ,
 wherein performing the second LBT in the second beam direction is a function of a set of LBT parameters, and 
 wherein the set of LBT parameters is determined based on hybrid automatic repeat request received from the second WTRU. 
 
     
     
       17. The method of  claim 1 , wherein the second beam direction is opposite to the first beam direction. 
     
     
       18. The WTRU of  claim 9 , wherein the second beam direction is opposite to the first beam direction.